Hydrogenation of tall oil



Patented a. 12, 1948 HYDBOGENATION 0F TALL 01L Harding Bliss, Hamden,

Conn., and WillianfC. Sussky, Little Rock, Aria,

assignors to Dictaphone Corporation, New York, N. Y., a corporation ofNew York No Drawing. Application May 18, 1945,

. Serial No. 594,605

This invention relates to the production of relatively hard, fattymaterials from tall oil and, more particularly, to an improvedhydrogenation and extraction process for obtaining from tall oil a hard,fatty product such as stearic acid.

In the manufacture of paper pulp'by digestion of wood with alkalineliquors, and particularly in connection with the so-called sulphateprocess. a dark oily material known as tall oil is produced as aby-product. Tall oil consists chiefly of a mixture of roughly equalparts of unsaturated fatty acids and resin acids together with minorproportions of other components such as sterols. Because of its fattyacid content tall oil is a possible source of stearic acid and otherhard, fatty materials that may be obtained by hydrogenation ofunsaturated fatty acids such as those contained in tall oil.

Many processes have'been' proposed for treating tall oil in such manneras to recover a commercially useful hard, fatty material. One group ofpreviously proposed methods is directed toward separating or isolatingthe fatty acidcontent of the crude tall oil and then hydrogenating theseparated unsaturated fatty acids. Methods previously proposed forseparation of the fatty acids include fractional crystallization,fractional distillation at reduced pressures and/or steam distillation,and selective esterification. None of these processes has so far provensatisfactory for commercial operation.

Another group of previously proposed methods is directed to preliminarypurification of the tall oil followed by hydrogenation of the tall oilwithout any preliminary attempt to separate the fatty acids and resinacids in the crude tall oil. .In some cases elaborate pre-treatmentmethods have been suggested with a view toward obtaining a material thatmay be hydrogenated to give a high quality product but these methodshave proven to be either inadequate or excessively expensive when anattempt is made to carry them out on a commercial scale.

It is therefore an object of the, present invention to provide animproved process for producing a hard, fatty product from tall oil. Itis another object of the invention to provide an improved method forhydrogenating crude tall 011 which has undergone no previous refiningsteps. It is a further object of the invention to provide a processwherein hydrogenation is used in conjunction with a selective solvent toproduce a fatty product of relatively high melt-- ing point. Otherobjects of the invention will '7 Chime. (Cl. 260-915) be in part obviousand in part pointed out hereinafter.

The present method is based upon the discovery that 1,4-dioxane exerts aselective solvent action on the products of, the hydrogenation of tall011 and that its use makes possible a more effective separation of suchproducts. The dioxane may be added to the tall oil before it ishydrogenated or alternatively the tall oil may be first hydrogenated andthe hard fatty products separated out by means of dloxane. The use ofdioxane is of particular advantage in cases where it is desired tohydrogenate crude tall oil directly without any preliminarypurification.

In accordance with one embodiment of the present method a quantity ofdioxane, preferably between about one-third and two parts by weight ofsolvent per part of tall oil is mixed with crude tall oil and themixture hydrogenated at a relatively high temperature and pressure inthe presence of a finely divided, highly active catalyst. It has beenfound that by carrying out the hydrogenation of the crude tall oil at arelatively high temperature and pressure in the presence of such anactive catalyst a fatty product of relatively high melting point may beobtained. The reaction pressure during hydrogenation is preferablymaintained at between three hundred and two thousand pounds per squareinch and the reaction temperature is desirably maintained between about250 F. and 475 F. The catalyst used may comprise finely divided nickelor a mixture of copper and nickel suspended in a suitable medium such ascottonseed oil or fish oil. It has been further found that an improvedproduct may be obtained by carrying out the hydrogenation reaction in aplurality of steps. Crude tall oil is hydrogenated under the conditionsindicated above and the reaction conditions are maintained until therate of reaction falls below a predetermined minimum value. A furtherquantity of catalyst is then added to the reaction mixture andhydrogenation continued under the same or similar operating conditionsfor a further period of time. It has been found that the degree ofsaturation of the product may be substantially increased by a secondhydrogenation-step of this character. Further hydrogenation steps stillfurther increase the satura tion of the product, but ordinarily it willnot be economical to use more than two hydrogenation steps.

In carrying out the hydrogenation reaction the mixture in tall oil andcatalyst is preferably heated during the initial stages of the reaction"i 3 to a temperature in the lower portion of the above-stated range, 1.e. 250' F. to 325 F. As the reaction proceeds the temperature is raisedand reaches a maximum at or near the end of the reaction. The maximumtemperature attained should desirably 'fall in the range of 350 F. to475 F.

The quantity of catalyst used may vary over a considerable rangedepending upon the type of catalyst used and to some extent upon thescale of operations. Where small quantities of tall I oil are beinghydrogenated a somewhat larger percentage of catalyst should be used.Typical proportions of catalyst are given in the following specificexamples. In general it has been found that the catalyst should bepresent to the extent of about 0.05% to 5% by weight of the mixture.

Owing to the presence of dioxane in the reaction mixture, the product ofthe hydrogenation reaction separates into two phases, a highlyhydrogenated solid waxy phase and an oily liquid phase containing the.resin acids and other unsaturated acids. Thus, by the use of thissolvent in the proper quantities, a fatty product may be more easilyobtained which contains a relatively high proportion of saturated fattyacids. As pointed out above the preferred proportions of dioxane liebetween about one-third and twoparts by weight of solvent per part ofcrude tall oil. If the solvent added exceeds about two parts per part ofcrude tall oil, there will usually be no appreciable phase separationafter hydrogenation. As the proportion of solvent is reduced the amountof the solid waxy phase that separates out increases, but its puritydecreases correspondingly. It was found that when the solvent ratio wasreduced to one-third part of solvent per part of tall oil or less bothphases were solid and difficult to handle. Moreover, the waxy phase wasof such low purity as to make the use of solvent of doubtful benefit.However, within most of the stated rangee, i. e. onethird to two partsof solvent per part of tall oil, there is sharply defined separation ofthe waxy phase and this waxy phase is about 50% to 80% hydrogenated.

In order to point out more fully the nature of the present invention thefollowing example is given of a preferred mode of carrying out theinvention: 450 grams of crude tall oil having an iodine value of 258were mixed with 450 grams of 1,4-dioxane and 11.2 grams of a catalyst.(The iodine values given in the present example were determined by the.method described in Ind. Eng. Chem., Anal. Ed, 16, 371 [1944]). Thecatalyst used comprised a suspension of finely divided nickel particlesin fish oil and contained about 24% nickel and 76% of the fish oil. Itis sold commercially by the Rufert Chemical Company and is identified bythe manufacturer as No. 1771.

The mixture of crude tall oil, catalyst and dioxane was charged into apressure vessel and hydrogenated at a pressure of about 1000 pounds persquare inch gauge and a maximum temperature of 390 F. The temperaturewas raised over a period of time from room temperature to the statedmaximum of 390 F. The hydrogenation was continued for .a ,periodof 136minutes..

After removal from the pressure vessel and 6 :12" cooling the reactionproducts separated into two phases, a solid phase and a liquid phase.The solid phase was cream-colored and waxy whereas the liquid phase wasblack and somewhat less viscous than the material originally charged tothe reaction vessel. The two phases were separated and the solventdioxaneremoved by distillation. Upon analysis it was found that the waxysolid material of the solid phase had an iodine value of 138 indicatingthat it was 46.5% hydrogenated. The titer of the solid was 52.4 C. Theliquid phase, on the other hand, had'an iodine value of 228, a titer of42.4 C. and was only 11.6% hydrogenated. It is therefore apparent thathydrogenation in the "presence of dioxane is accompanied by a separationof the more hydrogenated harder phase which is relatively rich instearic acid.

The selective solvent action of the dioxane is not dependent upon itspresence in the hydrogenation step, that is to say, a hydrogenated crudetall oil may after the hydrogenation step be mixed with suitablequantities of dioxane to give the desired phase separation. Thus, thehydrogenation of the crude tall oil, or even of a refined tall oil maybe carried out under the conditions described above, and thehydrogenated product mixed with dioxane to give a separation of a solid,waxy phase containing a relatively high proportion of saturated fattyacids such as stearic acid.

From the foregoing description it is apparent that the present inventionprovides an effective method of hydrogenating crude tall oil to yield ahard fatty product containing a relatively large proportion of saturatedfatty acids. The crude tall oil is used directly and no expensive andelaborate pre-treatment process is required. The use of dioxane as aselective solvent produces a sharp separation between the saturatedfatty acids and the unsaturated fatty and resin acids, thus giving arelatively high yield of the desirable hard fatty product. If desired,the hydrogenation may be carried out in a plurality of steps to produceeven higher yields of the fatty acids.

Since the present invention may have many embodiments and since manychanges may be made in the embodiments described above, it is to beunderstood that the foregoing description is to be interpreted asillustrative only and not in a limiting sense.

We claim:

1. A method of producing a. hard, fatty product from tall oil whichcomprises forming a mixture of tall oil and 1,4-dioxane containing from0.3 to 2.0 parts of dioxane by weight per part of tall oil,hydrogenating the mixture in the presence of a finely divided metalcatalyst at an elevated temperature and pressure, cooling the and talloil, hydrogenating said mixture in the presence of afinely divided metalcatalyst at an elevated temperature and pressure, cooling the resultingproduct to cause said product to separate into a resin-containing liquidphase and a fatty solid phase, and separating said fatty solid from saidresin-containing liquid.

3. A method of producing a hard, fatty product from tall oil whichcomprises hydrogenating tall oil oin the presence of a finely dividedmetal catalyst at an elevated temperature "and pressure, cooling theresulting product, mixing said product with an approximately equalquantity of 1,4-dioxane to cause said product to separate into aresin-containing liquid phase and a fatty 5 solid phase and separatingsaid fatty solid from said resin-containing liquid.

4. A method of producing a hard, fatty product from tall 011 whichcomprises forming a mixture of tall oil and 1,4-dioxane containing from0.3 to 2.0 parts by weight of dioxane per part by weight of tall oil,hydrogenating said mixture in the presence of a finely divided metalcatalyst at a pressure between 300 and 2000 pounds per square inch,maintaining the temperature of the mixture during hydrogenation between250 F. and 475 F., cooling the reaction product to cause the product toseparate into a resin-containing liquid phase and a fatty solid phase,and separating said fatty solid from said resin-containing liquid.

5. A method of producing a hard, fatty product from tall oil whichcomprises forming a mixture of tall 011 and 1,4-dioxane containing from0.3 to 2.0 parts by weight of dioxane per part by weight of tall oil,hydrogenating said mixture in the presence of a finely divided metalcatalyst at a pressure between 300 and 2000 pounds per square inch,raising the temperature of the mixture during hydrogenation to between350 F. and

475 F., cooling the reaction product to cause the product to separateinto a resin-containing liquid phase and a fatty solid phase, andseparating said fatty solid from said resin-containing liquid. 6. In amethod of producing a hard, fatty prodproximately equal quantity ofdioxane to cause a The following references are of record in 6 a uctfrom tall oil by hydrogenating said tall oil in the presence'of acatalyst at an elevated temperature and pressure to form a hydrogenatedtall oil from which said fatty product can be recovered, the step ofmixing with said tall 011 from .3 to to 2.0 parts by weight of dioxaneper part by weight of tall oil to cause separation of said fatty productfrom said hydrogenated tail oil. 7 In a method of producing a hard,fatty product from tall oil by hydrogenating said tall oil in thepresence of a catalyst at an elevated temperature and pressure to form ahydrogenated tall oil from which said fatty product can be recovered,the step of mixing with said tall oil an apseparation of said fattyproduct from said hydrogenated tall oil.

HARDING BLISS, WILLIAM C. SUSSKY.

REFERENCES CITED file of this patent: V

UNITED STATES PATENTS Number the

